Sreenu,
Pretty vague question. Unfortunately, vague questions are likely to receive vague answers: "It depends...". I am unable to answer until you clarify.
Try this. Log onto any ECC system, enter the command "SEARCH_SAP_MENU". Enter the term "planning". You will be presented with a list of transactions that contain that word. Review the list.
Review each transaction that interests you. If the transaction does not make sense, research further by searching in http://help.sap.com
Once you have done your basic research, and you actually have a specific question, come back with your question.
Best Regards,
DB49